Pakistani rescue workers carry a blast victim at the site of a blast in Faisalabad, Pakistan on Tuesday.

Pakistan's Taliban said they exploded a car bomb that killed at least 25 people and damaged an office of Pakistan's main intelligence agency in Faisalabad, the country's third-largest city.

The car detonated at a gas station near the office of the Inter-Services Intelligence Directorate, or ISI, triggering explosions of compressed natural gas cylinders, senior city official Tahir Hussain said by telephone. The blasts collapsed buildings in the area, where the local office of the state-run Pakistan International Airlines also is located. Television networks showed smoking rubble of the gas station and nearby buildings. "People are trapped under debris because several buildings were badly damaged," Hussain said.

More than 100 people were injured in the bombing, Zulifqar Ali, a spokesman for the Edhi rescue service in Faisalabad, said by telephone.

Faisalabad, in Punjab province about 135 kilometers (84 miles) west of Lahore, had before today largely been spared the militant attacks that have struck the country's capital, Islamabad, its largest cities, Karachi and Lahore, and its ethnic Pashtun zone along the western border with Afghanistan.

The Taliban and allied militant groups have conducted scores of bombings and gun attacks on police, army and intelligence facilities since 2007, when the army battled armed militants in the Lal Masjid, or Red Mosque, in Islamabad.

Army Offensives

Violence escalated two years later after the army launched offensives to end Taliban control of two mountainous regions — the Swat Valley and South Waziristan. More than 3,900 people have been killed in attacks since October 2009, when the Waziristan offensive began, according to a compilation maintained by the New Delhi-based South Asia Terrorism Portal.

Militants killed at least 47 people in bombings of ISI offices in Lahore and Multan in 2009.

Faisalabad, a textile hub of more than two million people, has suffered heavily from electricity and gas shortages that have crimped operations at its many industrial plants. Punjab generates more than half of Pakistan's economic growth and is home to about half of the country's 180 million people.